Cardiovascular disorders

II./4.1.: General introduction, epidemiology

Already the ancient Egyptians tried to recognize diseases by observing the “sounds” of the body, but a systemic auscultation of heart and respiratory system, what lead to the identification of the cardiac defects, has become widespread only after the invention of the stethoscope by a French physician, René Laënnec, at the beginning of the 19th century. So the diseases of heart valves has been known by the medicine for centuries, and the recent several decades brought a very significant breakthrough in the non-invasive and invasive diagnostics as well as therapy of these diseases. The prevalence of heart valve diseases is continuously growing in both the developing and the developed world. Their number in the developing countries is rising in parallel with the growing populations, due to the unchanged high incidence of rheumatic carditis.

Although rheumatic etiology has receded in the developed countries, but degenerative, senile alterations of the valves have become more frequent with the aging of the population. Based on American epidemiologic studies of the turn of century, the prevalence of moderate to severe heart defects in the age group between 18 and 44 years is only 0.7%, while among those over 75 years it already reaches 13.3%. The largest European survey, the Euro Heart Survey showed that the most frequent heart defects diagnosed by echocardiography among hospitalized or outpatients with a mean age of 65 years include aortic stenosis (AS) and mitral regurgitation (MR) (Drawing 1). A very high number of patients with a severe heart valve disease require hospital care in order to mitigate their symptoms and treat their heart defect by an intervention or surgery.

Drawing 1: Fibrous rings of heart. Location of aortic and mitral valves at the heart’s base. (1) Valva semilunaris anterior; (2) Valva semilunaris dexter ; (3) Valva semilunaris sinister; (4) Valva semilunaris sinister; (5) Valva semilunaris dexter; (6) Valva semilunaris posterior; (7) Cuspis anterior ostium atrioventiculare dexter; (8) Cuspis posterior ostium atrioventriculare dexter; (9) Cuspis septalis ostium atrioventriculare dexter; (10) Cuspis anterior ostium atrioventriculare sinister; (11) Cuspis posterior ostium atrioventriculare sinister

Both in conservatively and in surgically treated patients with valvular defects the leading cause of death is cardiac failure. Further components of mortality include sudden cardiac death, arrhythmias, stroke, endocarditis and the postoperative complications. The number of biologic and mechanic artificial heart valve implantations and surgical valve plastics has doubled worldwide in the last two decades. Interventional solution of heart defects began 25 years ago with balloon mitral valvuloplasty, and the development and use of interventions for transcatheter aortic valve replacement and other techniques for treating mitral regurgitation show an exponential growth.

The defects of cardiac valves can be divided to disorders of their opening (stenoses) and a failure of their closure (insufficiencies or regurgitations). These abnormities may also be present concomitantly on the same valve, or different defects may exist combined in the same patient. Complaints reported by the patients are usually aspecific: shortness of breath, effort dyspnea, fatigue, chest oppression, arrhythmias, dizziness, syncope, and the most varying symptoms of heart failure. The conventional methods of cardiologic diagnostics, such as physical examination, auscultation for assessing the sounds and murmurs of heart valves and pulmonary congestion; ECG for detecting arrhythmias as well as dilatation, hypertrophy, pressure- or volume-related strain of cardiac chambers, and thoracic X-ray continue to be essential for demonstrating heart defects.

Due to the astonishing advancements of non-invasive imaging techniques (two- and three-dimensional echocardiography, computer tomography, magnetic resonance) in the last decade, cardiac catheterization has lost its importance in demonstrating heart valve diseases and assessing their hemodynamic consequences. These non-invasive methods provide very rich information on the anatomical and functional anomalies, and therefore most patients get to the hemodynamic laboratory only for a possible interventional therapy of their heart defect, or for a preoperative coronary angiography. The important role of loading tests (ergometry and stress echocardiography) in choosing therapeutic strategy primarily for patients with yet asymptomatic significant defects or those with moderate to severe symptomatic defects is supported by more and more data of the literature.